Automatic tuning arrangement



Jan. 6, 1942. I J. KUPERUS 8,83

AUTOMATIC TUNING ARRANGEMENT Filed D60. 16, 1938 INVENTOR J/QN KUPE 5ATTORNEY Patented Jan. 6, 1942 AUTOMATIC TUNING ARRANGEMENT Jan Kuperus,Eindhoven, Netherlands, assig'nor, by .mesne assignments, to RadioCorporation of America, New York, N. Y., a corporation of DelawareApplication December 16, 1938, Serial No. 246,061

In Germany December 28, 1937 2 Claims.

The invention relates to a radio receiving apparatus adapted to beautomatically tuned to a number of predetermined stations by means of astation selector consisting of a keyboard, a selector disc or a similardevice.

Radio receiving apparatus with automatic tuning are already known inwhich the spindle of the tuning condensers has mounted on it a pluralityof profiled discs which each corresponds to one of the stations to whichthe receiver can be automatically tuned. In such arrangements the tuningmeans are usually coupled to a motor driven shaft in any suitable mannerand a plurality of station discs are mounted on the shaft. Thecircumference of each disc consists of two arcs with different radii,the centers of which are located in the axis of the shaft. Usually, afeeler is provided and arranged to move over the circumference of eachdisc. The feeler cooperates with two contact elements located on eitherside thereof. It the feeler is in contact with one portion of thecircumference of the disc, it engages one of the contact elements withthe result that the driving motor is energized for operation in onedirection.- If, on theother hand, the feeler is in contact with theother portion of the circumference of the disc it engages the othercontact element and thereby causes the motor to be operated in theopposite direction.

The above described device has the drawback that due to the contactbetween the feelers and the discs there occurs a rather considerablefriction. Besides, due to the movement over the circumference of thediscs the feelers become rapidly worn, so that danger of incorrecttuning arises.

The object of the invention is to provide a radio receiving system withcompletely automatic tuning wherein, upon attainment of the desiredtuning, the sense in which the tuning means are driven and the stoppingof these means are determined, as in the above described device, by theposition of a switch or of a plurality of switches but wherein the saiddrawbacks of the known device are avoided.

According to the invention, the switch or switches are operated for thispurpose, for each of the predetermined stations, by the movement of apermanent magnet under the influence of the attraction of a profiledbody which consists, at least partly, of magnetic material and whichis-moved, simultaneously with the tuning means, by the motor withrespect to the magnet.

The invention is preferably carried into eflect attraction of themagneticportion of the profiled body on the one hand and under theinfluence of a retroactive force on the other hand the magnet followsthe. profile of the magnetic portion of the profiled body without cominginto contact with the latter. The said retroactive force may beobtained, for example with the aid of a spring but it is preferablyformed by the attractive force between the magnet and a body of magneticmaterial located opposite said magnet.

The invention will be explained more fully by referring to the singlefigure of the accompanying drawing which represents, by way of example,one embodiment thereof.

In the device shown in the drawing the contact tongue 6 has securedto-it a permanent magnet 13 instead of a feeler. A disc 2 which ismounted on a spindle 'l by which the tuning means are actuated and whosecircumference consists of two arcs 3 and 4 of different radii is whollymade of magnetic material so that the magnet I3 is attracted by thedisc. Opposite the magnet is arranged a strip 14 of magnetic materialwhich exerts a retroactive force on the magnet.

So long as the portion 3 of the circumference of the disc is oppositethe magnet I 3, the attrac- 1 tive force exerted on the magnet by thestrip l4 exceeds the force exerted by the disc so that the magnetoccupies the upper position and the contact tongue 6 is pressed againstthe contact tongue I. If the switch 9 is closed, the field winding ll ofthe motor is switched into circuit in this case with the result that thespindle l is driven in clockwise direction.

If, on the other hand, the magnet is *located opposite the portion 4 ofthe circumference of the disc, the attractive force exerted by the discexceeds the force exerted by the strip II with they result that thecontact tongue 6 is pressed against the contact tongue 8 and, if theswitch 9 is closed, the winding II is excited, the, spindle I beingdriven in this case in the opposite sense.

When the point 12 at which the radius of the circumference is abruptlyaltered, is opposite the magnet the attractive force of the disc isequal to that of the strip II with the result that the magnet occupiesthe intermediate position and the windings," and ii are both switchedout of circuit.

The invention is not limited to the described practical example and maybe modified in many ways. Thus, it is not necessary that the whole insuch manner that imder the influence of the of the disc 2 should consistof magnetic material but it may also consist of a magnetic portion and anon-magnetic portion so that only part of the circumference of the discexerts an attractive force on the magnet whereas the latter is notattracted by the remainder. If in this case the non-magnetic portion ofthe circumference of the disc is opposite the magnet, the latter israised under the influence of the retroactive force. It is also possibleto use, instead of a disc, any other profiled member which is movable insome way or other with respect to the magnet. The single requirementthis member has to satisfy is that different portions of the surface ofthe member which is moved past the magnet should exert on the magnetdifierent forces of attraction. I

Furthermore, the retroactive force need not be exerted by a member ofmagnetic material; it may also be obtained in any other manner, forinstance, by means of a spring.

I claim:

1. In a selector control mechanism, switching means movable between twoextreme positions and arranged to close a first circuit when in oneextreme position and to close a second circuit when in the other extremeposition, said switching means when in a released condition beingarranged to assume an intermediate position in which neither of saidcircuits is closed, means for applying a substantially constant force tosaid switching device which tends to bring the switching device into oneof its extreme positions, rotatable magnetic means mounted in operativerelationship to said switching means and rotatable with respect thereto,said rotatable means having a sector providing suflicient magnetic forceto said switching device to overcome said constant force and bring theswitching device into its other extreme position, a second sectorproviding insuflicient magnetic force to overcome said constant forceand a third sector connecting said first two named sectors which variesthe magnetic force gradually from a value insufficient to overcome saidconstant force at one of its ends to a value sufiicient to overcome saidconstant force at the other of its ends, an intermediate part of saidconnecting sector providing a magnetic force which balances saidconstant force in which position of said rotatable means the switchingdevice assumes its intermediate position.

2. In a selector mechanism, a rotatable control shaft, a cam disc atleast a portion of which is composed of magnetic material, said discbeing eccentrically mounted on said shaft, a body of magnetic materialmounted substantially in the plane of said disc but spaced from thedisc, a permanent magnet Ieeler mounted for movement in the spacebetween the disc and said body, said disc being arranged with respect tosaid body so that for approximately one half of a complete cycle ofoperation thereof said permanent magnet is drawn toward it and forapproximately the other half of a complete cycle of operation thereofthe permanent magnet is drawn toward said body there being provided atleast one position of said disc wherein the permanent magnet assumes aposition of equilibrium between the disc and saidbody, and switchingmeans adapted to be selectively operated in accordance with theoperation of said permanent magnet so that one of said switching meansis closed only when the permanent magnet is drawn to a position nearestthe disc and the other switching means is closed when the permanentmagnet is drawn to a position nearest said body.

JAN KUPERUS.

